The Science of Lipstick
by starlight.moon.princess
Summary: In which there is lipstick, and Sherlock genuinely needs to kiss John for science. (John may have other motivations, but that's not the point. The science is.) :: Johnlock


**From the kink meme:** _All I really care about is seeing Sherlock put on a longwear lipstick and make out with John for scientific purposes._

**Also for the OTP Bootcamp on the BBC Sherlock Fanfiction Challenges Forum (19. "What do you want this time?")**

* * *

"JOHN!"

John Watson sighed as his roommate came into view. Sherlock had decided that he needed to interview his latest suspect alone, and John had been relieved – he needed some time to clean the apartment, make sure all of Sherlock's spare body parts were in the fridge and not in the dishes. He'd even hoped that he would be able to get some sleep out of it – the clinic wasn't busy at the moment, and Sarah tended not to call him in during a case unless there was an emergency.

Of course, now that he could hear Sherlock screaming for him, he realised that he should have known better than to hope for something so extraordinary.

"John do you have any long lasting lipstick?"

He had thought he understood Sherlock – at least, as far as anyone could – but that question proved him completely wrong.

"Sherlock, what the hell are you talking about?"

"No, of course you wouldn't," he continued distractedly. "You and Sarah never did get that far, and you've never actually gone into her room when you stay at her apartment. No problem, I managed to grab Ms Marten's. Actually, that would allow for a better sample, seeing as that is what she was wearing when she claimed to be-"

"Sherlock!" John barked, interrupting the detective's rambling.

"Right, of course. I need you to kiss me John."

John blinked at his flat-mate, and then blinked again. Sherlock wasn't blurry or dissolving into nothingness, which meant he wasn't hallucinating. A pinch to his arm confirmed that he wasn't asleep and in the middle of a dream, either. Which meant-

"Not right now, of course," Sherlock continued blithely, ignoring the gaping man staring at him in shock, "I still have to apply the lipstick. It's the only way to know if Ms Marten was telling the truth. Just give me a moment, and I'll be ba-"

"The truth about what?" John finally managed to ask. He had been going for outraged, but the shock just made him weak and ready to faint. "Sherlock, why exactly to you need to kiss me and what does it have to do with Delilah Marten?"

Sherlock sighed impatiently. "Ms Marten claims that she was 'making out' with her boyfriend at the time the murder happened, but the Yard took her in for question just a few minutes later and her lipstick was immaculate according to the tapes. She says that it's because of some sort of long lasting lipstick that she's been using, and I have to make sure she's telling the truth. You _know_ I have to confirm whether she's telling the truth, John, and this is the perfect way!"

"Sherlock, you can't just tell a person that they have to kiss you!" John _finally_ managed to exclaim.

"Why not?" Sherlock asked, sounding genuinely curious for once. Before John could reply to his question, Sherlock continued, ignoring his outraged look, as usual. "You can't seriously tell me that it's because you're straight – you're not, if the looks you've been throwing Lestrade's arse when he's bent over a body are any indication. By the way, I doubt that's proper crime scene etiquette – you should really control yourself. And we both know you're attracted to me, you have been since the first time we went to Angelo's, you know, for the Study In Pink, as you titled it on your blog. So really John, I don't see what's the problem – apart from the fact that I haven't had the chance to apply the lipstick yet, of course."

He shouldn't have been surprised, he really shouldn't have. It was Sherlock after all – of _course_ he'd managed to deduce John's feelings for him. Really, the fact that he'd managed to keep quiet about it till now should have been the only shocking thing about the whole affair. But John had really thought that he'd managed to keep his feelings hidden well enough that the world's only consulting detective wouldn't have noticed – the fact that he was bi? Sure. The fact that he was in love with Sherlock? Not so much.

But Sherlock was Sherlock – he just _had_ to prove him wrong.

He sighed in defeat. "Fine," he muttered. "Go apply the lipstick."

* * *

It was only when Sherlock came out of the bathroom that John realised the mistake he'd made by telling Sherlock to go apply Ms Marten's lipstick. The other man's lips had always fascinated him. It wasn't his mistake – anyone would agree with him once they laid eyes on his lips, the way they looked so delicious and perfect to kiss.

And then Sherlock went and dressed them up in flaming red lipstick, and John couldn't control the groan that escaped him at the sight. Sherlock just looked so bloody _gorgeous_-

Before he could even blink, Sherlock had taken two quick strides across the room and was now standing just centimeters away from John. He bent his head, a hand reaching out to curl in John's hair, until he was only a hair's breadth away from John's lips.

And at John's intake of breath, Sherlock's lips were on his.

John had promised himself while Sherlock was off making himself pretty that he was going to keep this as platonic as possible. It was obvious that Sherlock didn't return his feelings, and he wasn't about to open himself up for even more embarrassment. But then Sherlock's lips touched his- and all memory of that promise fled.

Kissing Sherlock was like being in a dream world. He couldn't believe that he was awake and not hallucinating – here was his biggest fantasy being handed to him on a sliver platter. He could even fool himself into believing that the groan he heard from Sherlock as he slipped his tongue into John's mouth wasn't just a figment of his imagination.

But all good things came to an end, even kissing Sherlock. When they were both low on oxygen, Sherlock pulled away from him – John wasn't about to let something as insignificant as breathing come in the way of what was possibly the only time he'd get to feel Sherlock's lips on his – and said in a breathless voice, "That was perfect. How is the lipstick looking?"

And they were back to the same old routine.

"It looks perfect, Sherlock," John muttered, "Not even a smudge. I think you need a new suspect."

Sherlock stopped – just _stopped_ – for a moment and stared at John. He could almost see the wheels in the detective's brain turni-

"Of COURSE!" he exclaimed suddenly. "How could I not have seen it? It was staring right at me. Stupid, stupid, _STUPID_! I need to get to St Bart's right now, John; I'll be back in a few hours. We can continue the experiment then."

And without waiting for John to reply, he grabbed his coat and dashed out of the apartment.

A part of John wondered if he should follow him. But Sherlock's words had made it obvious that he wasn't expecting John's help, and besides, he needed the time to think over what he had said as he left.

Of everyone alive, it was perhaps John who spoke Sherlock most fluently. And even though Sherlock had said nothing of the sort, the fact that he had told him that they would be continuing the kissing experiment was evidence to support something John had never thought possible – Sherlock had some feelings for him. They probably weren't as strong as John's were for Sherlock – John sincerely doubted that Sherlock was in love with him – but he did have feelings for him all the same.

Processing that would take some time.

John was happy to let his brain start to process everything – it would work better if he was doing something, so he could continue with what he had been doing before Sherlock decided to turn his world upside down.

It was only after he had cleared all of the variety of body parts that littered the kitchen that he remembered that Sherlock had left 221B without clearing off the lipstick. He had no doubt that his best friend was getting some very interesting looks at the moment, not least from Molly – and Greg, if he had hit the breakthrough he thought he had.

For a moment, he debated calling Sherlock and reminding him of that before he invaded NSY and had an argument with Anderson and Sally over the lipstick. But it was only for a minute – he had no doubt that Sherlock would manage the lipstick situation with his usual superiority and narcissism, and he was planning to have the time of his life trying to get it off of Sherlock when he returned home from Bart's.

After all, he already been gifted his greatest fantasy – he doubted anyone would fault him for changing it just a little bit to accommodate the new developments in their relationship.

* * *

**I hope you guys liked it! As always, please don't forget to drop a review on your way out :)**


End file.
